Electronic printed circuit boards (PCBs) commonly have a board with electronic components mounted thereon that can generate a considerable amount of heat due to electrical power consumption. The heat must be dissipated from the components and the board to ensure proper functioning of the components and to prevent damage to any part of the PCB.
A variety of techniques have been developed to dissipate the heat. For instance, one low-cost technique simply allows the source of the heat to transfer the heat by convection to ambient air. However, this technique has a relatively low effectiveness. To enhance the effectiveness of dissipation by convection, a fan is added to force the air to flow over the component. A heat sink or heat spreader may be attached to the component to further enhance heat dissipation by conducting the heat away from the heat source to a surface area (larger than that of the component) from which the heat may be dissipated to the air. For even greater heat dissipation enhancement, increasingly sophisticated techniques have been developed, including the use of heat pipes, active refrigeration, liquid cooled plates and spray cooling. Each such enhancement, however, is offset by an added cost.
It has been necessary to accept the added cost for enhanced heat dissipation techniques because a significant trend in the electronics industry has been to continually increase the processing power and power consumption of electronic components, leading to increasingly greater needs for heat dissipation. An additional trend, however, has been to decrease the size of the components, resulting in greater heat dissipation requirements in smaller volumes. In addition to decreasing the size of the individual components, such components are also often closely packed together in PCBs or circuit board modules, leaving little room between components to place the often-bulky heat dissipation apparatus. Furthermore, multiple PCBs in a single circuit board module may be closely stacked one on top of the other, leaving little or no room between the PCBs for the heat dissipation apparatus, even though the technique of flowing air between the stacked PCBs is insufficient to adequately cool the components therein.